1. Field
This application relates to apparatus and methods for winding coils. More particularly, this application relates to an apparatus and methods for controlling coil winding parameters.
2. State of the Art
U.S. Pat. No. 2,634,922 to Taylor describes the winding of flexible wire, cable or filamentary material around a mandrel in a figure-eight pattern such that a package of filamentary material is obtained having a plurality of layers surrounding a central core space. By rotating the mandrel and by controllably moving a traverse that guides the wire laterally relative to mandrel, the layers of the figure-eight pattern are provided with aligned holes (cumulatively a “pay-out hole”) such that the inner end of the flexible material may be drawn out through the payout hole. When a package of wire is wound in this manner, the wire may be unwound through the payout hole without rotating the package, without imparting a rotation in the wire around its axis (i.e., twisting), and without kinking. This provides a major advantage to the users of the wire. Coils that are wound in this manner and dispense from the inside-out without twists, tangles, snags or overruns are known in the art as REELEX (a trademark of Reelex Packaging Solutions, Inc.) -type coils. REELEX-type coils are wound to form a generally short hollow cylinder with a radial opening formed at one location in the middle of the cylinder. A payout tube may be located in the radial opening and the end of the wire making up the coil may be fed through the payout tube for ease in dispensing the wire.
U.S. Pat. No. 5,470,026 describes a coil with a payout hole that has a larger angular opening in the first layer and decreases in angular size in layers wound around inner layers, and also describes a correction of a payout hole angle due to a natural shift in the coil layers during the winding of the coil. The decrease in angular size controls a parameter referred to as “hole taper” and the correction of the payout hole angle controls a parameter referred to as “hole shift”. Previously, hole taper and hole shift were calculated based on a predicted diameter of the coil as it is being wound. The assumed or predicted diameter of the coil was based on counting the number of layers of wire laid down on a winding mandrel and multiplying the number by the diameter of the wire, hereinafter referred to as a “per-layer” method or approach.
U.S. Pat. No. 7,249,726 describes another coil winding parameter referred to as “density”. Reelex coils are produced by placing a plurality of figure-eight's radially around the circumferences of the coil using coil parameters referred to as “gains” or “traverse speed offsets” or “speed offsets”. If, for example, a coil is produced using speed offsets that place the figure-eights 30° apart, then these figure-eights will be 2.094 inches apart on an 8-inch diameter mandrel and 4.188 inches apart when the coil diameter reaches 16 inches. As a result, the coil is less “dense”, in terms of number of figure-eights, in the outer (radially relative to the center of the coil) layers of the coil. The density parameter has been used to control (i.e., reduce) the speed offset after each layer of the coil is wound so that the coil can be formed with increasing numbers of figure-eights as the number of layers of the coil increases. As a result, the angular space between figure-eights decreases with increasing coil layers counts, increasing the density in layers after the first layer.
When using prior methods of winding filamentary material into coils, each of the parameters, known to adjust the hole shift, density, and hole taper parameters after the winding of each layer of the coil to obtain a relatively compact coil with a relatively straight (radially) payout hole of relatively uniform diameter. The amount of adjustment made to the hole shift, density, and hole taper parameters at each layer are based on a predicted coil diameter based on the diameter of the filamentary material being wound and the layer number in the coil.